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MBC+A issues/questions

695 Views 8 Replies 3 Participants Last post by  Ice Man
I have been having a couple of issues with the mbc+a set up. I have recently installed the Viggen IC so since then a few things have crept up. Like getting a fuel cut 5 weeks after installing the IC and in warmer weather 34C.
So I started from scratch to set up the mbc+a last night,
1. I closed off the anticipator.
2. Adjusted the mbc until I got fuel cut.
3. Backed off the mbc and did runs with no fuel cut. So ok.
4. Started to open up the anticipator.
5. (anticipator) at 1 3/4 turns the boost was 1/2 way on red and stayed there. At 2 full turns the boost was 1/2 in red but settled back to start of red. At 2 1/4 turns the boost was only to start of red. Q? The optimum setting is the one with the boost staying in 1/2 into the red even at high rpms? If boost drops to start of red, this is not good. Am I correct???
6. On one of the runs with 2 turns I got fuel cut in 2nd & 3rd gear!! wtf?
7. So I backed off the mbc just a hair.
8. Seemed to be fine after and I have been doing this for an hour so I went home.
9. This morning I set the anticipator back to the "1 3/4 turns position" to try and hold more boost. I was not even able to get in the red!!!
10. I then set it back to where it was at 2 turns, and it boosted 1/2 way in the red. What's going on here???
11. Just shaking my head here at work. help!

Any advice on set up. Am I missing something?
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Sounds a little like a boost adaptation problem.
Onc you have established stable boost through three adaptation runs, you might find a more stable setting. The droop could be a number of things. vac line leaking boost, BPV(if not upgraded) IC heatsoaking, turbo reaching its flow limitations, etc...

CCW is fully closed on +A and that is where you started from right?

You using WOT to tune the MBC?
WOT and partial throttle have different effects on boost and how fast the MBC reacts. The stock gauge is alos not the most accurate thing either.

Best to find the setting using WOT and go from there.
I actually meant last night runs with the IC heatsoaked

Adaptation runs:
2nd and 3rd gear are preferrable.

Using an uphill grade run WOT from 2700-4000rpms and repeat until max boost is stabilized.
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